package com.xjt.java.test;

import java.util.HashMap;
import java.util.Map;

public class NullHashMap {

	/**
	 * @param args
	 */
	public static void main(String[] args) {

		HashMap hm = new HashMap();
		hm.put(null, null);
		hm.put(null, null);
		hm.put("liqian", "haha");
		hm.put("a", null);
		System.out.println(hm);
		System.out.println(hm.containsKey("a"));
		System.out.println(hm.containsValue("haha"));
		System.out.println(hm.get("liqian"));

	}

}
